Leak Detection Pump (LDP) -V144- (LDP for tank ventilation system), activating

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Press --> button.
Indicated on display:

Fig 1: VAG1551 Scan Tool Display - Output Diagnostic Test Mode: Engine Code AYS (Leak Detection Pump -V144-)
Courtesy of AUDI OF AMERICA, INC.

The change-over valve in the LDP is activated for approximately 1 minute (clicks), unless --> button is pressed first to switch to the next actuator.

NOTE: The click can be heard by listening near the rear left wheelhousing.

If valve is not activated (does not click): See EXHAUST SYSTEM, EMISSION CONTROLS - 4.2L V8 (AKB, AUX, AYS) .